KR102349518B1 - A process for vaporizing liquid propane and a vaporizing system used therefor - Google Patents

Abstract

The present invention relates to a method of vaporizing liquid propane to supply liquid propane as a raw material to a naphtha cracking reactor, it is possible to reduce the pressure of liquid propane to a much lower pressure than in the conventional method, so that all Not only can the latent heat of evaporation or heat of vaporization be used as a refrigerant, but also heat energy consumed in the preheating process before being supplied to the naphtha cracking reactor can be reduced.

Description

Liquid propane vaporization method and vaporization device used therefor

This application was filed on 2017.11.24. Claims the benefit of priority based on the filed Korean Patent Application No. 10-2017-0158631, and all contents disclosed in the documents of the Korean patent application are incorporated as a part of this specification.

The present invention relates to a process for vaporizing and supplying liquid propane when used as a raw material for a naphtha cracker, and more particularly, to a method for more efficiently using the heat of vaporization generated in the vaporization process of liquid propane.

Naphtha crackers mainly inject naphtha with steam at a high temperature and apply heat over 1000℃ to break the carbon ring to produce ethylene and propylene, and by-products such as butadiene and BTX. With the soybean of shale gas, existing naphtha crackers often mix and use these gases as raw materials due to the drop in the price of materials that can be used as raw materials for ethylene production instead of naphtha, such as ethane, propane, and butane. There are also many cases where gas is designed as a raw material.

Naphtha crackers have many demand for low-temperature refrigerants for product refining. For example, the consumption of refrigerant at -40°C exceeds 40 Gcal/hr in the ethylene refining tower, and a significant amount of refrigerant is also required in the deethane tower or demethane tower.

On the other hand, gas raw materials such as propane are stored in a liquid state and vaporized before being injected into the reactor. At this time, heat sources such as steam or hot water are consumed. If this gas raw material is used by heat exchange with the refrigerant demanding destination, the effect of reducing both the heat source and the refrigerant can be obtained.

An object of the present invention is to provide a method for efficiently utilizing the vaporization heat of liquid propane as a refrigerant in using liquid propane as a raw material for cracking naphtha.

In addition, another problem to be solved by the present invention is to provide an apparatus for vaporizing liquid propane used in the method.

In order to solve the above problems, the present invention provides a method of vaporizing liquid propane to inject it into a naphtha cracking reactor as a raw material,

S1) vaporizing at least a portion of the liquid propane by reducing the vaporization point by reducing the liquid propane;

S2) using the vaporization heat due to vaporization of the liquid propane as a refrigerant;

S3) increasing the pressure of the gas by compressing the vaporized propane; and

S4) provides a method of vaporizing liquid propane, including the step of preheating the compressed propane gas.

According to one embodiment, the pressure of liquid propane is reduced to 7 kg/cm ² G or less in the decompression step S1), and the heat of vaporization by the liquid propane in the step S2) can be used as a refrigerant of less than 20 ° C. .

According to another embodiment, the pressure of liquid propane is reduced to 1 kg/cm ² G or less in the decompression step S1), and the heat of vaporization by the liquid propane in the step S2) can be used as a refrigerant of -20 ° C or less. have.

According to one embodiment, the utilization amount of the refrigerant using the heat of vaporization by the decompression of liquid propane in step S2) may be 0.05 Gcal/hr or more per 1 ton/hr of propane.

According to one embodiment, the propane gas in step S3) may be compressed to a pressure of ^{7 kg/cm 2 G or more.}

According to one embodiment, the shaft work for compression of the propane gas in step S3) may be 1 kW to 50 kW per 1 ton/hr of propane.

According to one embodiment, the amount of steam consumed for preheating the propane gas compressed in step S4) may be 0.08 Gcal/hr or less per 1 ton/hr of propane.

According to an embodiment, the propane gas compressed in step S3) may be preheated to a temperature of 100° C. or higher in step S4).

In addition, the present invention to achieve another technical task,

In the vaporization apparatus for vaporizing liquid propane and injecting it into a naphtha cracking reactor,

a pressure reducing device for vaporizing at least a portion of the liquid propane by reducing the vaporization point by reducing the pressure of the liquid propane;

a heat exchanger for utilizing heat of vaporization by vaporization of the liquid propane;

a compressor for compressing the depressurized propane gas; and

It provides an apparatus for vaporizing liquid propane having a preheating apparatus for preheating the compressed gas.

According to an embodiment, the preheating device may use steam as a heat source.

In the present invention, in the process for supplying a raw material to a naphtha cracking reactor by vaporizing liquid propane, by providing a compression process of the reduced pressure propane gas, the flowability of the reduced pressure propane gas can be maintained, so that the reduced pressure pressure can be greatly reduced. Therefore, the heat of vaporization can be used more effectively. In addition, it is possible to reduce the thermal energy consumed for additional vaporization and preheating of propane gas in the preheating process before the feed of the raw material to the naphtha cracking reactor.

1 schematically illustrates a vaporization process of liquid propane used in the prior art.
2 and 3 are schematic views of the vaporization process of liquid propane according to various embodiments of the present invention.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Since liquid propane (C3 LPG) is supplied in a liquid state during transport and storage, it is introduced through a vaporization process before entering the naphtha cracking reactor.

At this time, since liquid propane has a low vaporization temperature, some may be used as a refrigerant, but in the conventional process as shown in FIG. In the existing process, the vaporization point is lowered to a level that reduces the pressure of liquid propane (C3LPG) to about 9.8 → 8.3 kg/cm ^{2 G.} , the temperature difference from room temperature is small, so the value as a refrigerant is low. Therefore, it is not sufficiently utilized as a refrigerant, and a significant portion has been used in a method of additionally vaporizing with a heat source such as steam or high-temperature water.

The present invention, in order to solve this conventional problem,

S1) vaporizing at least a portion of the liquid propane by reducing the vaporization point by reducing the liquid propane;

S2) using the vaporization heat due to vaporization of the liquid propane as a refrigerant;

S3) increasing the pressure of the gas by compressing the vaporized propane; and

S4) provides a method of vaporizing liquid propane, including the step of preheating the compressed propane gas.

That is, in order to solve the problem of not being able to efficiently use the heat of vaporization generated in the vaporization process because the pressure was not sufficiently lowered in the vaporization process of liquid propane, by providing a compression process using a compressor such as a compressor after the depressurization process, It was made to control the flowability of the depressurized gas. As a result, in the decompression process, the vaporization point of liquid propane can be reduced to a level that can be sufficiently lowered, so that the amount of use as a refrigerant can be significantly improved by using the vaporization heat of liquid propane.

In addition, in the process of being used as a refrigerant, heat required for vaporization is received from the outside, and the temperature of propane gas is increased through the compression process, so the consumption of heat energy consumed in the preheating process before being supplied to the naphtha cracking reactor is also significantly reduced. can

2 and 3 show various embodiments according to the present invention.

According to one embodiment, in the decompression step, the pressure of liquid propane ^{may be reduced to 7 kg/cm 2} G or less, and the amount of the reduced pressure may be adjusted according to conditions such as a cooling temperature using the heat of vaporization. have.

The refrigerant using the heat of vaporization generated in this decompression process can be used as a refrigerant of less than 20 °C, for example, it can be used as a refrigerant for cooling a difference of 10 °C or more from room temperature, and can be used as a refrigerant of 0 °C or less depending on the degree of pressure reduction It can also be used as a refrigerant for cooling temperature.

For example, according to the process of FIG. 2, in the decompression step S1), the pressure of liquid propane is reduced to 7 kg/cm ² G or less, for example, 5 kg/cm ² G to 6.8 kg/cm ² G, In step S2), the vaporization heat by liquid propane may be used as a refrigerant of less than 20°C, for example, 10 to 18°C.

In addition, according to the process of FIG. 3, in the decompression step S1), the pressure of liquid propane is reduced to 1 kg/cm ² G or less, for example, 0.3 kg/cm ² G to 0.8 kg/cm ² G, the step S2) It can be used as a refrigerant of -20 ℃ or less, for example, -25 ℃ to -30 ℃ by using the vaporization heat by liquid propane in the.

For example, the heat of vaporization may be used as a refrigerant in a reactor extract such as an ethylene refining column, a demethane column, or a deethane column through a heat exchanger, or for cooling (prechilling) a raw material of a distillation column, a condenser of a distillation column, and the like.

According to an embodiment, the utilization amount of the refrigerant using the heat of vaporization generated in the decompression process may be 0.05 Gcal/hr or more per 1 ton/hr of propane, preferably 0.07 Gcal/hr or more per 1 ton/hr of propane, more preferably Preferably, it may be 0.08 Gcal/hr or more per 1 ton/hr of propane.

Also, according to an embodiment, the compressed propane gas may be compressed using a compressor such as a compressor to maintain the flowability of the depressurized propane gas. At this time, for the compression of the propane gas using a compressor, a shaftwork of 1kW to 50kW per 1 ton/hr of propane may be used, and preferably, a shaftwork of 3 kW or more and 35 kW or less per 1 ton/hr of propane. can be used.

In addition, through the compression process, the pressure of propane gas is usually compressed to a pressure of 7 to 8 kg/cm ² G or may be compressed to a pressure of 4 to 10 kg/cm ² G depending on the pressure of the downstream process, and the temperature is 8 It can rise to about ℃ to 100 ℃.

The propane gas compressed under the above conditions can be decompressed to a remarkably low pressure, so that liquid propane can be sufficiently vaporized, and the temperature is increased through the compression process to reduce the amount of thermal energy consumed in the preheating process.

According to an embodiment, the compressed propane gas may be introduced into the naphtha cracking reactor through a preheating process. In this case, the heat energy consumption of the heat source consumed for preheating may be less than or equal to 0.05 Gcal/hr per 1 ton/hr of propane. Conventionally, the reduced pressure was not low enough, so it was additionally vaporized through a heat source, so that the thermal energy consumption was higher than 0.09 Gcal/hr per 1 ton/hr of propane. On the other hand, in the present invention, the pressure can be reduced to a significantly lower pressure compared to the conventional decompression process, so that liquid propane can be sufficiently vaporized, and the temperature is increased through the compression process to reduce the amount of thermal energy used in the preheating process. .

In addition, the present invention provides a vaporization apparatus for using the vaporization method.

More specifically, the vaporization device according to the present invention,

In the vaporization apparatus for vaporizing liquid propane and injecting it into a naphtha cracking reactor,

a pressure reducing device for vaporizing at least a portion of the liquid propane by reducing the vaporization point by decompressing the liquid propane;

a heat exchanger for utilizing heat of vaporization by vaporization of the liquid propane;

a compressor for compressing the depressurized propane gas; and

and a preheating device for preheating the compressed gas.

According to an embodiment, the preheating device may use steam, high temperature water, an electric heater, etc. as a heat source, but is not limited thereto, and preferably steam may be used.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

<Comparative Example 1>

Propane was vaporized using the propane vaporization process shown in FIG. 1 .

Table 1 shows the temperature, pressure, and flow rate in each unit of the process shown in FIG. 1 . Hereinafter, the symbols mean the following.

C3LPG: liquid propane

C3VAP: gaseous propane

PRC: Propylene Refrigerant Compressor

PR: Propylene Refrigerant

L, M, 1, 2, etc. are line symbols.

<Example 1>

Liquid propane was vaporized using the propane vaporization process shown in FIG.

The heat of vaporization by reduced pressure was used as a refrigerant at 15.2° C., and the temperature, pressure, and propane flow rate of the unit used in the vaporization process are shown in Table 2.

<Example 2>

Liquid propane was vaporized using the propane vaporization process shown in FIG. 3 .

The heat of vaporization by reduced pressure was used as a refrigerant at -27°C, and Table 3 shows the temperature, pressure, and propane flow rate of the unit used in the vaporization process.

Table 4 compares the refrigerant temperature, the refrigerant utilization amount, the steam consumption amount and the compressor shaft work according to the processes of Comparative Example 1 and Examples 1 and 2.

As can be seen from the results of Table 4, according to the present invention, since it is possible to maintain the flowability of the decompressed propane gas by using a compression means such as a compressor in the compression step (S3), sufficient pressure reduction in the decompression step (S1) This is possible. Accordingly, the vaporization point can be significantly lowered in vaporization through the depressurization process of liquid propane, thereby remarkably improving the utilization of the heat of vaporization.

In addition, it can be seen that since the consumption of thermal energy for additional vaporization is reduced in the preheating step S4 by steam, the amount of steam consumption is also reduced by more than half compared to the conventional method (Comparative Example 1).

As described above in detail a specific part of the present invention, for those of ordinary skill in the art, it is clear that this specific description is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (10)

In the method of vaporizing liquid propane to inject as a raw material into a naphtha cracking reactor,
S1) vaporizing at least a portion of the liquid propane by reducing the vaporization point by reducing the liquid propane;
S2) using the vaporization heat due to vaporization of the liquid propane as a refrigerant;
S3) increasing the pressure of the gas by compressing the vaporized propane; and
S4) A method of vaporizing liquid propane, comprising the step of preheating the compressed propane gas. The method of claim 1,
In the decompression step S1), the pressure of liquid propane is reduced to 7 kg/cm ² G or less, and in the step S2), the vaporization method of liquid propane is used as a refrigerant of less than 20° C. by using the vaporization heat of the liquid propane. . The method of claim 1,
In the decompression step S1), the pressure of liquid propane is reduced to 1 kg/cm ² G or less, and in the step S2), the vaporization of liquid propane is used as a refrigerant of -20° C. or less by using the vaporization heat of the liquid propane. Way. According to claim 1,
The vaporization method of liquid propane, wherein the utilization amount of the refrigerant using the heat of vaporization by the decompression of the liquid propane in step S2) is 0.05 Gcal/hr or more per 1 ton/hr of propane. According to claim 1,
In the step S3), the propane gas is ^{compressed to a pressure of 7 kg/cm 2} G or more. The vaporization method of liquid propane. The method of claim 1,
A method of vaporizing liquid propane in which the shaftwork for compression of the propane gas in step S3) is 1 kW to 50 kW per 1 ton/hr of propane. According to claim 1,
The vaporization method of liquid propane in which the consumption of steam consumed for preheating the propane gas compressed in step S4) is 0.08 Gcal/hr or less per 1 ton/hr of propane. According to claim 1,
The vaporization method of liquid propane in which the propane gas compressed in step S3) is preheated to a temperature of 100° C. or higher in step S4). In the vaporization apparatus for vaporizing liquid propane and injecting it into a naphtha cracking reactor,
a pressure reducing device for vaporizing at least a portion of the liquid propane by reducing the vaporization point by reducing the pressure of the liquid propane;
a heat exchanger for utilizing heat of vaporization by vaporization of the liquid propane;
a compressor for compressing the depressurized propane gas; and
A liquid propane vaporizer having a preheating device for preheating the compressed gas. 10. The method of claim 9,
The vaporization device of liquid propane in which the preheating device uses steam as a heat source.

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